Answer:
The Bible does not specifically talk to us about whether or not flirting is wrong, so what we should do is examine the definition of flirting. According to Merriam-Webster, flirting is "a) to behave amorously without serious intent, or b) to show superficial or casual interest or liking." It is synonymous with the word trifle, which is something of little value. The next thing we should examine is what people are usually trying to accomplish when they flirt. Are they trying to get attention from others, whether it is negative or positive? Are they attempting to show sexual interest or attraction? Do they see it as “innocent fun,” even if they or the other person is involved with someone else, even married?

Having casual contact with someone while purposely entertaining sexual undertones can be dangerous for us spiritually. Although most people believe that as long as nothing physical takes place, what goes on in our minds is irrelevant, the Bible tells us otherwise. “But I say, anyone who even looks at a woman with lust in his eye has already committed adultery with her in his heart. So if your eye – even if it is your good eye – causes you to lust, gouge it out and throw it away. It is better for you to lose one part of your body than for your whole body to be thrown into hell” (Matthew 5:28-29).

Sin begins in our minds and then moves to our hearts. Matthew 12:35 tells us that “a good person produces good words from a good heart, and an evil person produces evil words from an evil heart.” It is a fact that whatever we surround ourselves with, whatever we indulge ourselves in, and whatever we fill our minds with is what we will become. This is why Philippians 4:8 says, “Fix your thoughts on what is true and honorable and right. Think about things that are pure and lovely and admirable. Think about things that are excellent and worthy of praise.”

Although flirting is almost always described as “harmless,” it rarely, if ever, actually is. The first thing to consider is what people generally think about those who flirt. A woman who flirts, for example, will develop a reputation as being promiscuous. She will find that other women look at her as a threat and take an instant disliking to her. A man who flirts will be viewed as a womanizer who is not interested in serious relationships. Anyone who flirts may enjoy the attention, but the interest shown to that person is almost exclusively sexual and will probably lack any sense of respect.

The Bible tells us that we are to be a good example, showing others the love of Christ through our behavior (Ephesians 5:1-2). It is possible that a man or woman who is being flirted with has been struggling with lustful thoughts themselves. When a person of the opposite sex is hanging on them, winking at them, touching them, or showing off their body to them, it will make the person's struggle all the more difficult. The Bible strongly warns us against tempting others to sin (Matthew 18:7). We should do all we can to bring others into God's Kingdom and never do anything that would cause a person to stumble in his Christian walk (Romans 14:21). First Corinthians 10:31 reminds us, “Whatever you eat or drink or whatever you do, you must do all for the glory of God.”